In recent years, bidirectional communication over networks that communicate packets has increased accompanying the development of information technology. For example, IP telephony, which uses a voice over internet protocol (VoIP) function that enables verbal communication over the internet by an exchange of packetized voice data over networks that communicate packets, has become prevalent. For service providers, the monitoring and management of the communication quality of IP telephony services is important.
Networks that communicate packets have wireless intervals and in such networks, wireless communication apparatuses may be used as terminals on the network. In this case, packet delay at the wireless intervals is assumed to occur, however, to identify which portion of the wireless intervals is the cause of the delay, information that is included in the packets only when the packets are in the wireless intervals is necessary. Consequently, even if a packet on a wired interval is captured, it is not clear which portion of the wireless intervals is the cause of delay.
Conventionally, technology identifies an end terminal to be the cause of delay, based on the packet reception count at the end terminal and the count of packets passing at a gateway (see, for example, Japanese Laid-Open Patent Publication No. 2010-220048). A related technology determines the execution interval of processing identified as the cause of failure and facilitates power savings, based on the interval of the intermittent operation of a sensor node on a wireless network (for example, see Japanese Laid-Open Patent Publication No. 2008-15722).
Nonetheless, with the technologies described above, packets have to be monitored at the wireless communication apparatus that is the end terminal and in the wireless intervals on the network communicating packets. As a result, a monitoring apparatus has to be disposed in downstream wireless intervals of the communication network and since the number of monitoring apparatuses becomes huge, the cost also increases.
Meanwhile, when packets from the wireless interval to a wired interval pass through a relay device, the information that the packets have while in the wireless interval is lost. Consequently, even if packets are monitored along upstream wired intervals of the network, which portion of the wireless intervals is the cause of delay cannot be identified.